This Lab to Marketplace SBIR Phase I Phase II Fast Track Application has as its long- term objective to establish ultrasound as a safe, effective, and non-invasive method for assessing fracture risk, an important component in clinical management of osteoporosis. Osteoporosis afflicts over 20 million people in the U.S., and is responsible for more than 275,000 hip fractures annually. Currently, the primary means for assessment relies on densitometric techniques. These methods subject the patient to ionizing radiation, are relatively expensive, and do not always provide good estimates of bone strength. Ultrasound offers several potential advantages. It is non- ionizing and relatively inexpensive. Moreover, since ultrasound is a mechanical wave and interacts with bone in a fundamentally different manner than electromagnetic radiation, it may ultimately be able to provide more accurate estimates of bone strength and fracture risk compared with current densitometric methods. The goal of this research is to develop a new ultrasound system for bone assessment that is not only accurate but also highly reproducible. The system will assess the heel bone (calcaneus) distal forearm employ a novel positioning device that is foot-size based. The technology is designed to achieve both high reproducibility, as well as analogous regions of interest among different individuals to be compared. This is crucial given the high degree of heterogeneity that exists in the calcaneus. This research should enable the widespread detection of osteoporosis and fracture risk, and will find application not only in the U.S. but worldwide as well. The specific aims of this Lab to Marketplace Fast Track SBIR Application are to demonstrate the feasibility of a novel positioning device which in conjunction with CyberLogic's NTD technology to accurately and reproducibly estimate BMD at the calcaneus. This will be achieved by clinical testing in Phase I using a laboratory prototype that incorporates the patented positioning technology. This will if successful, be followed by fabrication of a clinical device in the first year of Phase II, followed by 24 months of extensive Phase II clinical testing, which will include comparison of ultrasound data in subjects with and without fragility fractures. Finally, the last year of Phase II will include submission to FDA of a 510(k) application. The ultimate goal of this research is to commercialize this novel heel ultrasound device and to bring it into worldwide use for a simple, safe and effective instrument for bone density estimation and fracture risk assessment.